Background: Maternal depression can be detrimental to infant development. Structured home visiting initiated either in pregnancy or soon after the birth by a professional has led to better outcomes for mothers and their children but some vulnerable families may respond more favourably to a local volunteer. The value of volunteer support provided in the UK by Home-Start for maternal well-being is noted in qualitative studies, but there is no evidence of its impact from trials. The support is not structured and both the frequency and content of visits may vary. Methods: A cluster randomized study allocated Home-Start local schemes to intervention or control conditions. Mothers in all areas were screened at routine health checks in late pregnancy. In intervention areas names of those scoring 9+ on the Social Disadvantage Screening Index were passed to Home-Start to be offered a volunteer. Not all those offered the support accepted the offer. In control areas no support was offered. Research assessments were conducted at 2 and 12 months. The outcomes were major or minor depression occurring between 2 and 12 months (Structured Clinical Interview for Diagnostic and Statistical Manual – Third Edition – Revised) and depression symptoms at 12 months (Edinburgh Postnatal Depression Scale). Three groups were compared: supported, case-matched controls and those offered but not receiving support. Results: Almost one-third experienced depression during the time period. Volunteer support had no identifiable impact on the emergence of maternal depression from 2 to 12 months or on depression symptoms when infants were 12 months. The major predictor of both was depression identified at 2 months. Conclusions: It was not found that informal support initiated following screening for disadvantage in pregnancy reduced the likelihood of depression for mothers with infants.